use std::io;

fn fibonacci(n: u64) -> u64 {
    if n <= 1 {
        return n;
    }
    fibonacci(n - 1) + fibonacci(n - 2)
}

fn main() {
    let mut input = String::new();
    println!("请输入要计算的 Fibonacci 数字: ");
    io::stdin().read_line(&mut input).unwrap();
    let n: u64 = input.trim().parse().unwrap();
    println!("{}", fibonacci(n));
}
